The present invention relates to vehicle occupant protection systems, and is directed to an apparatus for sensing a vehicle occupant to provide information useful for control within an occupant protection system.
Vehicle occupant protection systems that have an actuatable protection device are known in the art. The actuatable protection device of such a system is actuated upon the occurrence of a condition for which a vehicle occupant is to be protected. An example of a condition for which a vehicle occupant is to be protected is a vehicle crash.
One type of actuatable protection system includes an air bag module mounted within a vehicle such that an air bag of the module is inflatable within an occupant compartment of the vehicle. The air bag is inflated upon the occurrence of a condition, such as a vehicle crash. Another type of actuatable protection system has a seat belt extendable across a vehicle occupant and includes an actuatable device, such as a pretensioner, to move at least a portion of the seat belt relative to the occupant. The pretensioner removes slack from the seat belt to limit occupant movement, and is actuated upon the occurrence of a condition such as a vehicle crash.
An actuatable occupant protection system includes one or more sensors for sensing one or more parameters that are indicative of a condition for which the vehicle occupant is to be protected. For example, one sensor is a crash sensor that provides a signal indicative of a vehicle crash condition. The one or more sensors provide signals to a controller. The controller evaluates the signal(s) and determines whether to actuate the associated protection device.
One type of actuatable protection system has one or more adjustable aspects that are adjusted to change the actuation (i.e., deployment) of the protection device. For example, in a system that includes an air bag, the deployment profile of the air bag is adjustable. The adjustable aspects regarding the deployment profile of the air bag may include adjustment of a timing sequence for inflation, adjustment of pressure within the air bag during inflation and upon completion of inflation, and adjustment of air bag position with respect to the occupant.
To make determinations regarding adjustment, one or more characteristics of an occupant are sensed or are derived from occupant sensory information. Examples of occupant characteristics include: size of the occupant, weight of the occupant, position of the occupant, and distance between the occupant and a vehicle component surface (e.g., an air bag module).
Turning attention, for the moment, to the issue of distance determination, distance determination is typically accomplished by some form of ranging sensor. Ranging sensors can have various configurations. One type of ranging sensor is an ultrasonic ranging sensor. Another type of ranging sensor is an infrared ranging sensor.
Although many sensor systems are known, there are continuing needs for improvements and efficiencies in techniques and costs.
In accordance with one aspect, the present invention provides a vehicle occupant sensor apparatus that includes means for gathering an image of an occupant. The image has focus attributes. A focal plane associated with the means for gathering is at a distance from the means for gathering. The apparatus also includes means for determining position of the occupant relative to the focal plane utilizing the focus attributes.
In accordance with another aspect, the present invention provides a vehicle occupant sensor apparatus that includes an imager that collects an image of an occupant and that outputs a signal indicative of the collected image. The image has focus attributes. A focal plane associated with the imager is at a distance from the imager. A two-dimensional high-pass filter is operatively connected to the imager to provide a signal indicative of high frequency content of the imager signal. A multiple frame temporal filter is operatively connected to the imager to provide a signal indicative of image size conveyed by the imager signal. A position determination component is operatively connected to the two-dimensional high pass filter and the multiple frame temporal filter to determine position of the occupant relative to the focal plane utilizing the signal indicative of high frequency content of the imager signal the signal indicative of image size conveyed by the imager signal.
In accordance with another aspect, the present invention provides a method of sensing a vehicle occupant. An image of an occupant is gathered. The image has focus attributes. A focal plane is at a distance from a location of image gathering. Position of the occupant relative to the focal plane is determined utilizing the focus attributes.